Amaranth contains a natural pigment called amaranth, which exists in cell vacuoles. The chloroplast in the cell is green, because of its high content, so the green color masks the red color, and the raw amaranth is dark green. As mentioned above, heat destroys cell membranes and cell walls, decomposes chloroplasts, and destroys the structure of chlorophyll, resulting in red exudation in vacuoles.